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Purpose: Beckwith-Wiedemann syndrome (BWS) is a developmental disorder caused by dysregulation of the imprinted gene cluster of chromosome 11p15.5 and often associated with loss of methylation (LOM) of the imprinting center 2 (IC2) located in KCNQ1 intron 10. To unravel the etiological mechanisms underlying these epimutations, we searched for genetic variants associated with IC2 LOM.Methods: We looked for cases showing the clinical features of both BWS and long QT syndrome (LQTS), which is often associated with KCNQ1 variants. Pathogenic variants were identified by genomic analysis and targeted sequencing. Functional experiments were performed to link these pathogenic variants to the imprinting defect.Results: We found three rare cases in which complete IC2 LOM is associated with maternal transmission of KCNQ1 variants, two of which were demonstrated to affect KCNQ1 transcription upstream of IC2. As a consequence of KCNQ1 haploinsufficiency, these variants also cause LQTS on both maternal and paternal transmission.Conclusion: These results are consistent with the hypothesis that, similar to what has been demonstrated in mouse, lack of transcription across IC2 results in failure of methylation establishment in the female germline and BWS later in development, and also suggest a new link between LQTS and BWS that is important for genetic counseling.

Background Fluoroscopic catheter ablation of cardiac arrhythmias in pediatric patients exposes the patients to the potential risk of radiation considering the sensitivity of this population and its longer life expectancy. We evaluated the feasibility, safety, and efficacy of accessory pathway (AP) ablation guided by CARTO3 electroanatomic mapping (EAM) system with both cryoenergy and radiofrequency (RF) energy in order to avoid x-ray exposure in pediatric patients. Methods We included 44 patients (mean age: 13.1 ± 3.3 years); nine of 44 presented concealed AP. An electrophysiological study with a three-dimensional EAM reconstruction was performed in every patient with a venous transfemoral direct right atrium approach or an arterial transfemoral retrograde approach to reach the mitral annulus. In two patients with left-sided AP, the ablation was performed via a patent foramen ovale. Results A total of 47 APs were present, left sided in 45% (21/47) of cases (15 lateral, one anterior, three posteroseptal, and two posterolateral) and right sided in 55% (26/47; one anterior, three anterolateral, one posterolateral, three lateral, five para-Hisian, 12 posteroseptal, and one anteroseptal). Ablation without the use of fluoroscopy was successfully performed in every patient (33 with RF and in 11 with cryoenergy). No complication occurred. At a mean follow-up of 16.0 ± 11.7 months, we observed seven recurrences, three of them successfully re-ablated without fluoroscopy. In one case cryoablation of a para-Hisian AP was ineffective in the long term. Conclusions Three-dimensional EAM allowed a safe and effective fluoroless AP ablation procedure in a pediatric population both with RF and cryoenergy.

Background Anatomical considerations and risks related to x-ray exposure make atrioventricular nodal reentrant tachycardia (AVNRT) ablation in pediatric patients a concerning procedure. We aimed to evaluate the feasibility, safety, and efficacy of performing fluoroless slow-pathway cryoablation guided by the electroanatomic (EA) mapping in children and adolescents. Methods Twenty-one consecutive patients (mean age 13.5 ± 2.4 years) symptomatic for AVNRT were prospectively enrolled to right atrium EA mapping and electrophysiological study prior to cryoablation. Cryoablation was guided by slow-pathway potential and performed using a 4-mm-tip catheter. Results Sustained slow-fast AVNRT was inducible in all the patients with a dual AV nodal physiology in 95%. Acute success was achieved in 100% of the patients with a median of two cryo-applications. Fluoroless ablation was feasible in 19 patients, while in two subjects 50 seconds and 45 seconds of x-ray were needed due to difficult progression of the catheters along the venous system. After a mean follow-up of 25 months, AVNRT recurred in five patients. All the recurrences were successfully treated with a second procedure. In three patients, a fluoroless cryoablation with a 6-mm-tip catheter was successfully performed, while in the remaining two patients, a single pulse of 60 seconds of radiofrequency energy was applied under fluoroscopic monitoring. No complications occurred. Conclusions Combination of EA mapping systems and cryoablation may allow to perform fluoroless slow-pathway ablation for AVNRT in children and adolescents in the majority of patients. Fluoroless slow-pathway cryoablation showed a high efficacy and safety comparable to conventional fluoroscopy guided procedures.

Background: Total cavopulmonary connection (TCPC) is performed in patients having a single ventricle to allow the passive flow of systemic venous blood to the lungs. Interventional catheterization is needed to treat residual defects or complications. Aims: We discuss our results concerning 68 patients who had had TCPC from January 1995 to December 2010. Methods: Initial and follow-up catheterization data were reviewed retrospectively. Mid-term results were evaluated by means of angiography and/or CT scan. Results: Mean age at TCPC was 5 years (2.5–18); mean interval between TCPC and catheterization was 5.6 years (1.5–15). Sixty-nine catheterizations were performed in 53 patients. Eleven patients (21%) had low venous pressure, did not display a right-to-left shunt, and did not need any intervention. Fifteen patients (28%) had low venous pressure and only needed the closure of the fenestration. The remaining 27 patients (51%) needed the following interventions: embolization of venous vessels prompting right-to-left shunt (n = 15), stenting or reconnection of pulmonary arteries (n = 5), stenting or recanalization of systemic veins (n = 11), other procedures (n = 5). In 3 patients the fenestration could not be closed due to high venous pressure. After the interventions oxygen saturation increased from 90.5%± 4.8% to 94.7%± 3.6% (P = 0.002). Conclusions: Our data show that 49% of patients with TCPC are in good condition late after surgery. However, half of these patients continue to need interventions generally aimed at suppressing stenoses at various levels of TCPC or at occluding vessels prompting right-to-left shunt. This population should enter a multicenter program aimed at identifying patients at risk. (J Interven Cardiol 2012;25:622–627)

Objective The objective of this study was to evaluate the technical feasibility, safety, and efficacy of the new device Amplatzer duct occluder II additional sizes (ADO II AS) for closure of patent ductus arteriosus (PDA). Background: Transcatheter device closure is the standard care for PDA. Currently available technology is not designed for closure of small PDA in young children. Methods From April to July 2011, seven children (five females, median age 1.5 years, median weight 11.4 kg) underwent PDA closure with the ADO II AS. Six had isolated PDA, one had PDA associated with preductal coarctation. We evaluated early and short-term results. Results All but one PDA was closed via an antegrade approach. Mean fluoroscopy and procedural times were 8.0 ± 3.9 and 49.8 ± 27.9 min, respectively. No complications occurred. Immediate trivial residual shunt was present in one patient. In all devices, the retention disks laid flat against the walls of the pulmonary artery and aorta, without protrusion into the vessel lumen. The echocardiography performed after 24 hr did not show any residual shunt. At a median follow-up of 2 months, the PDAs were completely occluded without obstruction of the pulmonary arteries or aorta. Conclusions The new device ADO II AS was safely deployed with complete resolution of the PDA shunt. The lower profile and symmetry of this device allows for venous or arterial approach and smaller delivery catheter size. The ADO II AS might be a preferable alternative for closure of small-moderate PDAs. © 2012 Wiley Periodicals, Inc.

Aims Limited data exists on midterm results concerning paediatric interventions on stenotic or occluded systemic veins following indwelling lines, cardiac surgery, or catheterisations. The purpose of this study was to report our acute and intermediate results concerning patients with (Group A) and without (Group B) congenital heart diseases (CHD) over a 10-year period. Methods and results From January 2000 to December 2010, 32 patients (23 in Group A and nine in Group B, respectively) underwent 39 interventional catheterisations aimed to dilate or recanalise occluded iliofemoral veins, inferior or superior venae cavae. Initial and follow-up catheterisation data were reviewed retrospectively. Midterm results were evaluated by means of echography, angiography, and CT scan in all 15 and 17 patients, respectively. Median age and weight of all patients at catheterisation were five years (range 0.1-18) and 15 kg (range 2-60), respectively. Fifty-two stents were implanted in 29 patients (32 vessels). In 25 patients 28 vessels were occluded and required recanalisation. There were no major complications. In all but three patients it was possible to treat the lesion. There were two procedural complications (5.1%): one acute stent occlusion and one local dissection. At a median follow-up of 2.5 years (range 1-10) we observed six complications of stenting (11.5%): two fractures, two occlusions and two restenoses. Conclusions Interventional catheterisation of stenotic or occluded systemic veins grants good immediate results at a low rate of complication. Stent dilatation or recanalisation may open the vessel for use during future procedures. However, long-term results are yet to be established.

Chronic right ventricular (RV) pacing is associated with deleterious effects on cardiac function. In an observational multicentre study in children with isolated atrioventricular (AV) block receiving chronic ventricular pacing, the importance of the ventricular pacing site on left ventricular (LV) function was investigated. Demographics, maternal autoantibody status and echocardiographic measurements on LV end-diastolic and end-systolic dimensions and volumes at age 1 year) for isolated AV block. LV fractional shortening (LVFS) and, if possible LV ejection fraction (LVEF) were calculated. Linear regression analyses were adjusted for patient characteristics. From 27 centres, 297 children were included, in whom pacing was applied at the RV epicardium (RVepi, n = 147), RV endocardium (RVendo, n = 113) or LV epicardium (LVepi, n = 37). LVFS was significantly affected by pacing site (p = 0.001), and not by maternal autoantibody status (p = 0.266). LVFS in LVepi (39 ± 5%) was significantly higher than in RVendo (33 ± 7%, p < 0.001) and RVepi (35 ± 8%, p = 0.001; no significant difference between RV-paced groups, p = 0.275). Subnormal LVFS (LVFS < 28%) was seen in 16/113 (14%) RVendo-paced and 21/147 (14%) RVepi-paced children, while LVFS was normal (LVFS ≥ 28%) in all LVepi-paced children (p = 0.049). These results are supported by the findings for LVEF (n = 122): LVEF was

Background— The prevalence of genetic arrhythmogenic diseases is unknown. For the long-QT syndrome (LQTS), figures ranging from 1:20 000 to 1:5000 were published, but none was based on actual data. Our objective was to define the prevalence of LQTS. Methods and Results— In 18 maternity hospitals, an ECG was performed in 44 596 infants 15 to 25 days old (43 080 whites). In infants with a corrected QT interval (QTc) >450 ms, the ECG was repeated within 1 to 2 weeks. Genetic analysis, by screening 7 LQTS genes, was performed in 28 of 31 (90%) and in 14 of 28 infants (50%) with, respectively, a QTc >470 ms or between 461 and 470 ms. A QTc of 451 to 460, 461 to 470, and >470 ms was observed in 177 (0.41%), 28 (0.06%), and 31 infants (0.07%). Among genotyped infants, disease-causing mutations were found in 12 of 28 (43%) with a QTc >470 ms and in 4 of 14 (29%) with a QTc of 461 to 470 ms. One genotype-negative infant (QTc 482 ms) was diagnosed as affected by LQTS on clinical grounds. Among family members of genotype-positive infants, 51% were found to carry disease-causing mutations. In total, 17 of 43 080 white infants were affected by LQTS, demonstrating a prevalence of at least 1:2534 apparently healthy live births (95% confidence interval, 1:1583 to 1:4350). Conclusions— This study provides the first data-based estimate of the prevalence of LQTS among whites. On the basis of the nongenotyped infants with QTc between 451 and 470 ms, we advance the hypothesis that this prevalence might be close to 1:2000. ECG-guided molecular screening can identify most infants affected by LQTS and unmask affected relatives, thus allowing effective preventive measures.

In children, intracardiac loops are created to avoid a lead's fracture due to rapid body growth. Selective site pacing needs the insertion of two 4.1 Fr lumenless leads that do not allow direct manoeuvrability and should be extracted when tension on the lead occurs. We describe an easy, safe, and inexpensive technique to reposition the leads and generate new intracardiac loops.

Background— We evaluated the effects of the site of ventricular pacing on left ventricular (LV) synchrony and function in children requiring permanent pacing. Methods and Results— One hundred seventy-eight children (aged R =0.80, P =0.031). Pacing from the RV outflow tract/lateral RV predicted significantly decreased LV function (LV ejection fraction P =0.005), whereas LV apex/LV midlateral wall pacing was associated with preserved LV function (LV ejection fraction ≥55%; odds ratio, 8.26; confidence interval, 1.46–47.62; P =0.018). Presence of maternal autoantibodies, gender, age at implantation, duration of pacing, DDD mode, and QRS duration had no significant impact on LV ejection fraction. Conclusions— The site of ventricular pacing has a major impact on LV mechanical synchrony, efficiency, and pump function in children who require lifelong pacing. Of the sites studied, LV apex/LV midlateral wall pacing has the greatest potential to prevent pacing-induced reduction of cardiac pump function.

We describe a 59-year-old patient with Holmes heart (single ventricle with normally related great arteries). To our knowledge, this is the oldest patient in the literature with this rare congenital heart disease and the oldest one with single ventricle and unrestricted pulmonary blood flow who has developed Eisenmenger's physiology. A transesophageal echocardiographic examination showed a single large ventricle that was a morphologic left ventricle with a normally appearing aorta originating from this chamber and a normally related pulmonary artery arising from a hypoplastic right infundibulum located anteriorly-superiorly and to the left of the left ventricle. The cardiac catheterization confirmed the echocardiographic findings and revealed a pulmonary artery pressure of 160/60 mmHg. There were no systolic gradients across the pulmonary and aortic outflow tracts. The estimated pulmonary vascular resistance was 2720 dynes-sec-cm −5 . Oximetry showed oxygen saturation in the left ventricle of 84% and femoral artery saturation of 77.7%. Our report further demonstrates that pulmonary stenosis is not the ultimate determinant of prolonged natural survival in patients with single ventricle. Since this patient is too old for cardiopulmonary transplantation, we plan to follow him conservatively with medical therapy.

Total cavopulmonary connection (TCPC) is performed in patients having a single ventricle to allow the passive flow of systemic venous blood to the lungs. Interventional catheterization is needed to treat residual defects or complications. We discuss our results concerning 68 patients who had had TCPC from January 1995 to December 2010.Initial and follow-up catheterization data were reviewed retrospectively. Mid-term results were evaluated by means of angiography and/or CT scan. Mean age at TCPC was 5 years (2.5-18); mean interval between TCPC and catheterization was 5.6 years (1.5-15). Sixty-nine catheterizations were performed in 53 patients. Eleven patients (21%) had low venous pressure, did not display a right-to-left shunt, and did not need any intervention. Fifteen patients (28%) had low venous pressure and only needed the closure of the fenestration. The remaining 27 patients (51%) needed the following interventions: embolization of venous vessels prompting right-to-left shunt (n = 15), stenting or reconnection of pulmonary arteries (n = 5), stenting or recanalization of systemic veins (n = 11), other procedures (n = 5). In 3 patients the fenestration could not be closed due to high venous pressure. After the interventions oxygen saturation increased from 90.5%± 4.8% to 94.7% ± 3.6% (P = 0.002).Our data show that 49% of patients with TCPC are in good condition late after surgery. However, half of these patients continue to need interventions generally aimed at suppressing stenoses at various levels of TCPC or at occluding vessels prompting right-to-left shunt. This population should enter a multicenter program aimed at identifying patients at risk.

In a female foetus of 31 weeks we diagnosed a mass of 15 × 17 mm, occupying most of the left ventricular cavity, which did not cause arrhythmia, cardiac failure, or obstruction. After birth, we confirmed the presence of an intraventricular mass and performed 3D echocardiography to highlight the spatial relationship with cardiac structures. The mass had an unusual heart shape and was visibly smaller …

Aims Few data are available about selective-site pacing in children. A 4.1 Fr lead is now available: it has to be introduced through an 8.4 Fr steerable catheter, and it raises concerns as to the long-term patency of the subclavian vein. The aim of this study was to systematically evaluate the patency of the subclavian vein in children who had selective-site pacing by the SelectSecure Lead System (SSLS) for atrioventricular block and look for possible local early and late complications. Methods and results From June 2006 to January 2010, we implanted 20 patients. Mean age at implantation was 9 years (range 3–16), mean weight 31 kg (range 13–57). All patients received a dual-chamber pacemaker (PM). The patency of the subclavian vein was evaluated by ultrasound 1, 3, and every 6 months after the PM implantation. We also looked for oedema, swelling, changes in temperature or colour of the skin, and visible superficial circulation. Forty leads were implanted in 20 patients. After a median follow-up of 19 months (range 6–44), no clinical signs or symptoms of vein occlusion were detected in the whole population. None of the patients had an alteration of blood flow at Doppler examination. Conclusion The SSLS is a promising and safe system for permanent intracardiac pacing in paediatric patients. We show that it does not increase the risk of venous thrombosis. Until a venography study with a larger population and longer follow-up regarding venous patency and overall complications using SSLS will be performed, our results although promising have to be considered preliminary data.

Aims In pacemaker patients with Gram-positive occult bacteremia, it is reasonable to remove the whole stimulation system, but therapeutic decision is sometimes very challenging. Methods and results A young patient at 6 years of age underwent dual-chamber pacemaker implantation due to complete atrioventricular block after mitral valve replacement. He felt well until November 2008, when he suffered from febrile illness with blood cultures disclosing methicillin-resistant staphylococcus aureus strain. Repeated antibiotic courses were effective only in obtaining temporary remissions. Consecutive transoesophageal echocardiography examinations were inconclusive. A labelled leucocyte scintigraphy, showing increased captation along leads, was very helpful and critical in guiding our decision to extract leads. Conclusion In equivocal cases, or when the hazard of extraction procedure is presumably high, every accessory diagnostic tool (like scintigraphy with labelled leucocytes) is helpful in establishing a definitive diagnosis and in strengthening a somewhat difficult decision.

Aims The aim of this study was to evaluate the feasibility and reliability of selective-site pacing by means of a new lead system in a paediatric population. This lead system is composed of a 4.1 Fr, active-fixation lead and a steerable catheter that allows easy positioning in selective sites. Methods and results Thirty young patients (mean age 9.0 ± 4.5 years, range 2–16 years) received a single- (10) or dual- (20) chamber pacemaker. The 3830 lead was implanted successfully in the targeted chambers in all patients. The selective RV sites of pacing in 26 of the patients were: 18 mid-septum, 5 outflow tract, 1 low-septum, and 2 LEVO-RV-Apex. In all patients, an intracardiac loop was left in order to avoid stretching of the lead with growth. Mean follow-up duration was 11 ± 10 months. Atrial sensing and pacing thresholds were 3.2 ± 1.7 mV and 0.8 ± 0.6 V at 0.5 ms at implantation and 3.4 ± 2.1 mV and 0.6 ± 0.3 V at 0.5 ms at follow-up. Ventricular sensing and pacing thresholds were 12.1 ± 4.9 and 0.7 ± 0.4 V at 0.5 ms on implantation and 12.7 ± 6.1 mV and 0.8 ± 0.5 V at 0.5 ms at follow-up ( P = NS). No adverse events were reported. Conclusion Select Secure is a promising system for selective-site pacing in children.

Background. The long QT syndrome (LQTS), a leading cause of sudden death under 20 years of age, is due to mutations in genes which encode ion channels involved in the control of ventricular repolarization. In a prospective study on 34,000 neonates we found that a prolonged QT interval was associated with a 41 times greater risk for sudden infant death syndrome (SIDS) and, recently, in a case-control study on 201 cases of SIDS we found disease-causing LQTS mutations in 9.5% of the victims. Based on these results the Italian Ministry of Health is considering the possibility of introducing in the National Health Service an electrocardiographic (ECG) screening program in the first month of life to identify infants affected by LQTS. A realistic assessment of the prevalence of infants with LQTS becomes necessary. Methods. An ECG was recorded in the first month of life in 44,596 neonates. The QT interval was measured and corrected for heart rate according to the Bazett’s formula (QTc). In the neonates with a markedly prolonged QT (QTc ≥ 470 msec) molecular screening of the LQTS genes was performed. Results. A QTc between 440 and 470 msec was observed in 611 neonates (1.4%). A QTc ≥ 470 ms was found in 31 neonates (0.07%). Genetic analysis was performed in 28/31 (90%) neonates and LQTS mutations were identified in 14 of them (50%): 8 were LQT1, 4 LQT2 and 2 LQT3. Besides one de novo mutation, all other cases were familial and genetic analysis identified additional family members (37/72, 51%) affected by LQTS who had not been previously diagnosed. Within these 28 infants QTc was longer in the positively genotyped neonates (493±22 vs 479±6 ms, p=0.037) and a LQTS mutation was identified in all the neonates (n=5) with a QTc > 496 ms. Conclusions. An ECG performed in the first month of life, with genetic analysis in selected cases, allows early diagnosis of infants with sporadic and familial forms of LQTS, thus leading to institution of effective therapies aimed at preventing sudden death either in infancy or later on in life, not only in the neonates but also in their affected family members. This study also provides a first data-based estimate of LQTS prevalence, likely to be between 1/3,000 and 1/2,500 live births.

Purpose: Anatomical considerations and risks related to x-ray exposure make atrio-ventricular nodal reentrant tachycardia (AVNRT) ablation in pediatric patients a concerning procedure. We aimed to evaluate the feasibility, safety and efficacy of performing fluoroless slow pathway cryoablation guided by the electroanatomic (EA) mapping in children and adolescents. Methods: Twenty-five consecutive patients (mean age 13.8±2.5 years) symptomatic for AVNRT were prospectively enrolled to right atrium EA mapping and electrophysiological study prior to cryoablation. Cryoablation was guided by slow pathway potential and performed using a 4-mm tip catheter. Results: Sustained slow-fast AVNRT was inducible in all the patients with a dual AV nodal physiology in 96%. Acute success was achieved in 100% of the patients with a median of 2 cryo-applications. Fluoroless ablation was feasible in 23 patients, while in 2 subjects 50 and 45 seconds of x-ray were needed due to difficult vascular accesses. After a mean follow-up of 27.5 months AVNRT recurred in 6 patients. All the recurrences were successfully treated with a second procedure. In 4 patients a fluoroless cryoablation with a 6-mm tip catheter was successfully performed, while in the remaining 2 patients a single pulse of 60 s of radiofrequency energy was applied under fluoroscopic monitoring. No complications occurred. Conclusions: Combination of EA mapping systems and cryoablation may allow to perform fluoroless slow pathway ablation for AVNRT in children and adolescents in the majority of patients. Fluoroless slow pathway cryoablation showed a high efficacy and safety comparable to conventional fluoroscopy guided procedures.

Current catheter technology is not designed for closure of large patent ductus arteriosus (PDA) in low-weight infants. Percutaneous coil occlusion of PDA was previously attempted in a sick premature baby with multiple malformations.1 The new miniaturised device, ADO II AS (Amplatzer Duct Occluder II Additional Size), might avoid the risk of surgical closure of PDA in preterm babies.2 A male child was born with a weight of 1050 g; he …

transplantation 2 years ago, we treated him with digitalis, diuretics, and ACE-inhibitors. 6 months later, he had palpitations and an electrocardiogram showed paroxysmal supraventricular tachycardia (heart rate 180 bpm), which rapidly improved with intravenous verapamil (0·10 mg/kg). 1 year ago, he was admitted to our Intensive Care Unit because of worsening of ventricular function with cardiogenic shock. Intravenous dopamine improved his condition. After discharge, he was well for the next 4 months, then he became breathless on exertion and finally at rest. A transthoracic echocardiographic showed a ventricular ejection fraction of 0·49. Blood pressure was 165/90 mm Hg, pulse 102 beats/min. Room air arterial blood gas showed a pH of 7·34, PCO2 of 36 mmHg, PO2 of 40 mm Hg, and oxygen saturation of 70%. His haemoglobin was 22·9 g/dL and hematocrit 60%. Until seven months ago, he had severe rest dyspnea (IV NYHA Class). With his informed consent, oral amlodipine administration was started (5 mg once a day). During the first week of treatment, a symptomless decrease of blood pressure was noted (to mean values of 90/60 mm Hg). Thereafter a gradual increase was noted (110/80 mm Hg). There was also a gradual increase in his physical effort threshold. He can now go up a flight of 23 stairs at home, and he is self-sufficient again. A second echocardiographic examination showed a ventricular ejection fraction of 0·54. Patients with single ventricle usually die from heart failure, arrythmia, or suddenly. Long or short-term treatment with calcium-antagonists can worsen heart failure and increase the risk of death. In two controlled studies, amlodipine did not have any unfavourable clinical effects and reduced symptoms and improved physical efforts tolerance.

Introduction: Permanent junctional reciprocating tachycardia (PJRT) is an infrequent form of reciprocating tachycardia, almost incessant from childhood and usually refractory to drug therapy. Radiofrequency catheter ablation currently is the first-line therapy for PJRT, but its application in the septal region may be associated with complications. In contrast, cryoenergy has several advantages, such as the ability to test the effects of ablation while the lesion is still forming, thus reducing the number of ineffective, useless, and potentially harmful lesions. The aim of this study was to investigate the potential clinical utility of percutaneous cryoenergy catheter ablation for treatment of pediatric patients with PJRT. Methods and Results: Four patients (age 14 ± 5 years; mean ± SD) with a clinical diagnosis of PJRT underwent catheter cryoablation. The ablation was successfully accomplished in 4 (100%) of 4 patients. The mean ± SD number of cryoapplications was 1.8 ± 0.8, and from 1 to 6 cryomappings were performed for each permanent cryolesion. The successful site was in the mid-septal region (2 patients), at the coronary sinus orifice (1 patient), and in the middle cardiac vein (1 patient). No complications with cryoablation were reported, nor was there prolongation of the AH interval during cryomapping or cryoablation. No pain was reported by patients during the cryoenergy catheter ablation procedure. PJRT recurrence occurred in 1 patient who underwent a second successful cryoablation procedure. Conclusion: The outcomes of cryoenergy catheter ablation in these 4 patients treated for PJRT suggest that cryoablation is a safe, effective, and pain-free technique for treating pediatric patients with PJRT. (J Cardiovasc Electrophysiol, Vol. 15, pp. 263-268, March 2004)